Thermostatic switch



22.21 1936. J. E. CARLSON 2,033,093

THERMOSTATIC SWITCH Filed May 26, 1934 2 Sheets-Sheet l umiii INVENTOR JOHN E. CAR SON,

April 21, 1936. J. E CARLSON 2,038,098

THERMOSTATIC SWITCH Filed May 26, 1934 2 Sheets-Sheet 2 INVENTOR JOHN E. CARLsoN,

Patented Apr. 21, 1936 UNITED STATES PATENT OFFICE THERMOSTATIC SWITCH necticut Application May 26, 1934, Serial No. 727,654

4 Claims.

My invention relates to quick make and quick break switches primarily intended for use in incubators, brooders, refrigerators, etc.

In its preferred form it involves the use of an expansible bellows filled with a suitable fluid such as ether which is subjected to the temperature of the space which it is desired to govern. A toggle action switching device is spring actuated in one direction and in the other direction is actuated by the expansion of the bellows.

In certain cases where especially quick action is desired a part or parts of the toggle action device may be of thermostatic bimetallic metal which may in. some instances, but not necessarily, work in conjunction with the bellows. The switch contacts per so may be of either single or double break construction.

Fig. l is a vertical sectional view of one form of apparatus involving my invention in one form of its application, the parts being shown on a reduced scale.

Fig. 2 is a full sized sectional view showing the switch parts per se.

Fig. 3 is an exploded perspective view showing parts of the toggle action device.

Fig. 4 is a sectional and side elevation showing the mechanism of my invention.

Fig. 5 is a plan view and section on the plane of the line 5 5 of Fig. 4 showing the expansible bellows.

Fig. 6 is a plan view of the toggle action and switch parts per se.

Fig. 7 is a detail end view showing the switch contacts.

The expansible device i0 is preferably in the form of metallic discs with a chamber containing the expansible gas or fluid. This is supported in a frame ll suspended by a tube l2 from a bracket I3.

spectively the edge 25 of the insulating plate 20 and the edge or edges 26 at the tip of the arm l4. These edges are preferably thin to produce the approximate efiect of knife edges in the grooves of the spring 22.

A rod 21 within the tube l2 rests on the top of the expansible disc member ID. An adjusting screw 28 which has a threaded engagement in the lower part of the spring arm l4 engages the upper end of the rod 21. A set nut 29 may be provided to hold the screw 28 in such position as may be desired when the arm 14 is adjusted to the position required.

The parts in the drawings are shown in the position which they would occupy when the expansible disc ID is expanded. A stop 30 may be provided to limit the upward movement of the arm l4.

When the disc contracts the spring tension of the arm I4 moves the upper end of the arm ld' downwardly and the bowed spring 22 reverses the tension on the plate 20 so that the plate and the movable switch member iii are moved upwardly to close the circuit through the mechanism which it is desired to control.

By adjusting the screw 28 the initial tension of the arm l4 may be changed so as to cause the toggle action to take place at the desired change of temperature.

The device is shown in Fig. 1 installed in a chicken brooder having a suspended hood 3| with an interior member 32 whose wall supports the bracket 13 and attached parts. This hood may be provided with an opening 33 for access to the switch device and a door 34 for covering the opening.

It will be seen that the device is constructed in such a manner that it can be readily assembled and installed as aunit, being secured in place by one or more bolts such as 35.

By the use of such a thermostatic switch the temperature of the apparatus can be controlled as desired. In some cases it may be desirable to form the arm M of bimetallic metal so that the arm itself will be sensitive to thermal changes.

The bowed spring 22 is preferably V-shaped or otherwise formed so as to facilitate its insertion into the space between the edge 25 and the ends of the fingers 26, 26.

I claim:

1. In a thermostatic switch. a movable arm, a contact member secured to the outer end portion of said arm by a finger which is relatively more flexible than said arm and a bowed spring be tween the outer end portion of said arm and the adjacent edge of said contact. member to provide a snap action.

2. In a thermostatic switch, a movable arm, a contact member secured to the outer end portion 01' said arm by a finger which is relatively more flexible than said arm and a bowed spring between the outer end portion of said arm and the adjacent edge of said contact member to provide a snap action, said contact member including an insulating support secured to said finger. V

3. In a thermostatic switch, a movable arm, a contact member secured to the outer end portion of said arm by a finger which is relatively more flexible than said arm and a bowed spring between the outer end portion of said arm and the adjacent edge of said contact member to provide a snap action, said finger and bowed spring being at least one of them arrangedon each side of the other.

4. In a thermostatic switch, a support, a resilient arm having one end secured to-the support and the other and movable, spring fingers secured to the movable end of the arm and of greater resiliency-than the arm, a contact member carried by the spring fingers, stops for said contact'member carried by said support, a bowed spring interposed between the movable end of said arm and said contact member, and a thermostatic device having a part engaging said arm adjacent the end which is secured to the support for bending the arm and causing the contact to move with a snap action between said stops.

JOHN E. CARLSON. 

